Storage I/O is at the heart of modern data centers. Emerging
storage device technologies, such as solid-state disks (SSDs),
allows us to build servers that are capable of millions of I/O
operations per second. This trend shifts the bottleneck from I/O
devices to the host I/O path. However, today's I/O path in
virtualized and non-virtualized environments has been designed
for small numbers of cores, low device throughputs, and has been
tuned for single-application workloads.